Composting operations have become abundant across the country, producing valuable soil amendment material while effectively reusing waste materials. More recent operations are using variations of the ‘aerated static pile’ method to enhance the compost process by forcing and controlling air movement through the composting material. This requires a method of aerating the material by inducing air through the bulk material in a uniform manner.
Positive aeration systems introduce air at the bottom of a pile or windrow and force it upwardly until it is dispersed to the atmosphere or, if contained in an enclosure, treated for removal of noxious odors and volatile organic compounds (VOC) prior to release to the atmosphere. Negative aeration systems draw air downwardly through a pile or windrow allowing total capture of the process air for subsequent treatment by a biofilter or other means of odor and VOC removal. Some aeration systems reverse the air flow through a pile or windrow thus operating at times as a positive aeration system and, alternately, as a negative aeration system.
Conventional positive and negative aeration systems may consist of a plurality of parallel, equally-spaced pipes typically on centerline distances of 2′ to 6′ placed at the base of the composting material. The pipe walls typically contain holes less than 0.75 in. diameter on their surfaces at equal intervals along the length of the pipes. In some cases, pipes are placed beneath the pile of material with spigots extending upward from the pipes to the base of the composting material. In either case, these arrangements create a grid of openings from which air enters or leaves the composting material.
These current systems suffer from one or more faulty characteristics such as: high static head losses along the length of the pipes and across the small holes, high jet velocities within the material in the proximity of the pipe holes, difficult or impossible cleaning access to the internal surfaces of the pipes, clogging of the holes particularly in negative aeration, and the need to move and replace pipe prior to removal and/or replacement of the composting material.
Accordingly, what is needed is a novel system and method for efficiently providing uniform aeration to an aerated compost process that has a low operating cost, provides uniform air introduction and removal within a pile or windrow, simplifies cleaning and maintenance, and does not require manual manipulation of the aeration equipment during removal and replacement of the composting material. This novel system must contain all of the above features while allowing heavy equipment and the use of large buckets and other material handling equipment to traverse the aeration components without undue wear or damage.